Failure to maintain rail car hoses at a proper height above the rail structure is a significant cause of unintended air hose coupling separation leading to emergency braking and stopping of the train and sometimes even derailment. Obviously, emergency braking is a cause of time-consuming and costly train delays as a result of the need for a crew member to walk the length of the train looking for the cause. When an uncoupled air hose is discovered, the crew member must reconnect the coupling members or effect an emergency repair before returning to the engine.
To eliminate the problem, it is known to provide air hose straps interconnected between the coupler or other parts of the car and the end of the air hose. Known straps have a fastening system including wire clips which have a hooked end which fits through an aperture on a fixture on the air hose. The wire is then looped back through a selected aperture on the strap and then captured by the hooked end.
The looped portion of one of the prior art clips extends through an aperture in a bracket typically provided on the bottom of each rail car coupler. A second clip is provided which is preferably identical to the first. The looped portion of the second clip fits through an aperture integral with the glad hand fitting on the end of the air hose. If the straps have not been properly installed or should the strap material elongate over time, readjustment becomes necessary to avoid the risk that the air hose will strike a cross tie, a grade crossing, a switch or other track structure causing air hose separation.
While air hose support straps made of chain, steel cable or webbing can be used, the presently preferred approach is to use an elastomeric strap material capable of providing some give in operation. Polyurethane is a presently preferred strap material. Elongated spring clips as fastener members are provided for attachment of one of the ends of the strap to the railcar body and the opposite end to an apertured fitting at the end of the air hose.
Although these assemblies are effective in supporting the end of the air hose, a problem arises which leads to damage and ultimately to failure of the clips in service. This problem was investigated following field service reports of air hose support straps that had failed because of “bent or missing clips”.
The investigation revealed that over 95% of clip damage occurred to the clip connecting the bottom of the support strap to the air hose glad hand fitting. From analysis of a number of clips produced by different manufacturers, it was observed that the damage was a result of the clip being strained on the long sides of the clip (lateral loading) instead of along the long axis of the clip (longitudinal loading). The clips are much stronger when the load is applied on the clip ends rather than on its long sides.
The invention is based on a recognition of the cause of this lateral loading and to the means provided for eliminating it. Lateral loading occurs when the railroad car coupler is in the buff position as occurs when it is not under load. In this condition, the air hose support is slack, which allows a clip of prior art design to slide along its length through the glad hand aperture. When the coupler returns to the neutral or draft position, the load is applied to the side of the clip where it is weakest rather than its ends, bending the clip into an oblong or ovoid shape. Eventually, this causes the clip's locking integrity to be lost. It was observed that this type of lateral loading accounts for the majority of clip damage failures.